function Common() {}

Common.prototype.Logout = function(sitecoreID) {
new Ajax.Request('/sitecore modules/web/databases/dispatcher.aspx',
    {   method: 'post',
        postBody: 'command=logout&sitecoreID=' + sitecoreID,
        onSuccess: function(transport)
            {
                if (transport.status == 200)
                {
                   window.location = "/";
               }
            },
        onFailure: common.ShowError
    });
}

Common.prototype.ShowError = function(transport)
{
    //alert('test');
}

var common = new Common();